Scalable quantum hardware requires qubits that can be initialised, read out, and manipulated on short timescales with high fidelity. Semiconductor quantum dots (QDs) meet many of these criteria and, when embedded in microcavities, have shown strong performance for single-qubit control [1]. However, scaling to multi-qubit architectures remains difficult because each nanostructure is slightly different: spectral inhomogeneity and device-to-device variability obstruct deterministic coupling and gate operations between dissimilar qubits. 

This project tackles that bottleneck with a hybrid approach that couples QDs via microcavity exciton-polaritons [2] which are light-matter quasiparticles that combine the agility of photons with the interactions of excitons. By engineering a polariton “information bus” inside a microcavity, we aim to mediate controlled interactions between non-identical QDs, enabling fast, single-shot quantum non-demolition readout of individual spin qubits, universal single-qubit control, and high-fidelity two-qubit phase gates[3-6]. 

The research will span the full pipeline from device conception to quantum operation. We will design and fabricate the hybrid polariton-QD platform, optimise cavity and material parameters for strong, controllable coupling, and characterise the resulting devices using cryogenic microscopy and advanced optical spectroscopy. We will quantify how hybridisation influences qubit properties like coherence, addressability and cross-talk and we will establish protocols for robust gate implementation that tolerate inhomogeneity.  

Finally, we will demonstrate polariton-mediated quantum logic, benchmarking readout speed, gate fidelity, and scalability. Methodologically, the project blends experimental design with modelling and data-driven analysis. It will draw on semiconductor device design and nanofabrication, photonics and cryogenic techniques, and applied quantum information theory to translate microscopic interactions into working quantum functionality. The outcome will be a validated route to scaling QD-based qubits without demanding stringent spectral matching, opening a practical path towards integrated, photonics-ready quantum processors.